Had the same problem running on Win7x86Ran all .net updates (important and optional) from windows update (still didnt work after this)Disabled "COM + Event" service in msconfig utilityFinally tried disabling MS Security Essentials Active Protection and it finally starts.My best guess is that your AV Active protection might still be active?In any case, best of luck to you and post if you find a good fix (since i dont like having AV disabled).